This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A297225 #4 Dec 27 2017 15:38:43 %S A297225 1,9,24,57,182,535,1513,4415,12832,37110,107661,312229,904915,2623749, %T A297225 7607302,22054261,63940404,185379485,537454173,1558199157,4517574360, %U A297225 13097454856,37972451701,110090662857,319177485549,925367027389 %N A297225 Number of 3Xn 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 1 neighboring 1s. %C A297225 Row 3 of A297224. %H A297225 R. H. Hardin, <a href="/A297225/b297225.txt">Table of n, a(n) for n = 1..210</a> %F A297225 Empirical: a(n) = a(n-1) +2*a(n-2) +8*a(n-3) +6*a(n-4) +4*a(n-5) -6*a(n-6) -8*a(n-7) -8*a(n-8) +10*a(n-9) +4*a(n-10) -2*a(n-11) -3*a(n-12) +a(n-13) %e A297225 Some solutions for n=7 %e A297225 ..0..1..0..1..1..0..0. .1..1..0..0..0..0..0. .0..0..0..0..0..0..0 %e A297225 ..1..0..0..0..0..1..1. .0..0..0..1..1..0..0. .0..0..0..0..0..0..0 %e A297225 ..1..1..0..0..0..0..0. .1..1..0..0..1..1..0. .1..1..0..0..0..0..0 %Y A297225 Cf. A297224. %K A297225 nonn %O A297225 1,2 %A A297225 _R. H. Hardin_, Dec 27 2017